Differential spring conduit support



United States Patent FOREIGN PATENTS [72] Inventor Lawrence M. Talley [54] DIFFERENTIAL SPRING CONDUIT SUPPORT ABSTRACT: A differential spring for supporting a heavy flexible conduit such as a hose or water cooled electrical cable to 9 Claims, 5 Drawing Figs.

138/1 lOX dampens cable sway and offers gradually decreasing. support 138/1 10X and stiffening to the cable away from the termination.

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au PG 56 05 99 II I6 I PATENTEU usm 5 Ism SHEET l UF 2 NVENTOR. LAWRENCE M. TLLEY BY uwmll' Arron/m 1 f urmnrrmxr. srnrnc couourr surronr BACKGROUND OF THE INVENTION rubber or plastic and fabric, copper conductor strands, and an outer jacket which confines the cooling water. In someapplications a heat shield is used over vthe outer jacket.` n

Cables of this type are tenninated by soldering, brazing, or welding the copper or other metallic conductor strands to the terminals. Becauseof the configuration of the cable the terminated conductor strands are required to carry virtually the entire weightof the cable. A spiral spring `or rubber tube defining the hollow core offers little or no supportl to the cable. The spiral spring is generally attached to the terminals but because of its configuration offers little support or resistance to cable bending. The hollow tube is generally not attached to the tery minals, but endsv several inches away because of possible damage from the heat generated in soldering or otherwise terminating the copper conductors to the terminal. Neither ofthe hollow core defining means therefore is of material assistance in stiffening the cable or in 'assisting the copper strands to. carry the weight ofthe cable.

The problem of supporting thecable is accentuated in applications such as electric arc furnaces where the cables supplying the furnace are in almost continuous motion because of the large varying electric currents and the `motion of the furnace electrodes. Also the cables are stretched into a tight catenary when the furnace is tilted to a pouring position.

The cable tension and aggravating motion has been carried by the cable strands alone. The effect of the motion and tension is most severe at the terminals where the cable strands in many cases have been weakened by overheating and oxidation occurring in the terminating process.

y Prior cable supports have generallycomprised a rigid sleeve or similar device which supports acable in the area of a splice cable support is generally mounted'in a horizontal position to offer maximum support to the cable'asharp bend tends to be produced in the cable at the point where the cable is no longer supported by the rigid sleeve. when the cable is required to hang in a very pronounced arc as, for example, in a cable supplying an electric are furnace, the terminations are made vertical to avoid sharp bends. ln such cases the rigid sleeve support vertically mounted may cause a sharp bend in the cable when the cable is tightened by the furnace being tilted to the pouring position or when cable motion is produced by the large varying electric currents and the motion of the furnace electrodes. y

Problems quite similar to those noted above are encountered with hydraulic hoses that carry water and other liquids from place to place for cooling. firefighting and many other purposes. 1 f

SUMMARY OF THE INVENTION places, such as adjacent a termination, while allowing the conduit to bend in a substantially uniform arc of generous radius. A still more particular object is to providea support that will dampen yconduit motion minations.

thereby relieving stress at the ter-l l hereinafter.

Another object is the provision of-a cable support that may be mounted on the outside of an electrical cable or on the-inside of a hollow core electrical cable. Still another object is the provision of a cable support that allows the hollow core defining means of a water cooled electrical cable to be attached to the ten'nnals through the cable support to assist in supporting the cable. l l

A preferred fonn and embodiment of my differential spring comprises a plurality of spring wire sections having different flexibilities, and means for joining the sections together to form a series thereof. The series is arranged to have a first end section of minimum flexibility and to increase incrementally in flexibility in each section to a second end section of maximum flexibility. 'l

The differential spring may be on the outside or the inside of a terminated cable, hose, or similar conduit. The section of minimum flexibility is attached to the tennination. The section of maximum flexibility may be attached to the conduit, or if the di`erential spring is placed inside vthe. hollow core of a water cooled electrical cable the maximum' flexibility section may have its outer end attached to the hollow core defining means, for example a rubber tube, to enable the tube to assist in supporting the cable.

The differential spring is thus disposed along the flexible conduit in such a manner that maximum support is offered closest the termination and decreases in increments to offer support to the conduit while at the same time allowing it to assume a natural gentle arc as required by the particular application. Because the sections are essentially springs of different strength, conduit motion will be damped in such a manner that maximum damping occurs closest to the termination.

BRIEF DESCRIPTION OF THE DRAWINGS nected to an electrode of an electric arc furnace and sup.-

ported by a preferred form of differential spring; I y

FIG. 2 is a perspective of a preferred form of differential spring according to my invention;

FIG. 3 is a perspective partially cutaway of a terminated water cooled electrical cable having a rubber. tube that defines a hollow core in the cable within which is disposed a differential spring for supporting the cable; y

FIG. 4 is a perspective of a terminated water cooled electrical cable having a differential spring disposed about the exterior ofthe cable; and

FIG. 5 is a perspective of an alternate form of differential spring.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred form and embodiment of differential spring -l0 j is shown in FIG. Zand comprises in'this illustrative embodiment three separate sections 17, 18 and 19. Each section isv formed of a plurality of parallel, longitudinally-extending, resilient, spring wires 20. The wires 20 are preferably made of nonmagnetic stainless steel, bronze, brass or other resilient nonmagnetic material for reasons to `be disclosed more fully Separating and defining the sections 17, 18 and 19 are discs 22, 23, 24 which serve to guide and/or terminate the spring wires 20.' The sections 17, 18, 19 are made cylindrical in shape to conform to the cable or hose they will support. Sections 17, `18, 19 are constructed to have different numbers of spring wires 20 in each section. ln the example of FIG. 2, section 17 is provided with 18 spring wires, section 18with 12 wires and section 19 with 6 wires. The different numbers of wires in each section is most conveniently provided by passing a length of When used as illustrated in FIG. 3, the

A. wirethl/ rbugh one of the openings 25 in the disc 22 and passing the wire back through an adjacent opening 25 in disc 22 to for'rn"a loop as at 26. In the same manner the wire is passed through openings 25 in discs 22 and 23 to form loop 27 and then'through openings 25 in discs 22, 23 and 24 to fonn loop 28. The procedure is continued until a differential spring of 'the desired characteristics is obtained.

`The effect of the different numbers of strands of spring wire vin each section 17, 18, 19 is a different flexibility or resistance to bending in each of the sections. As shown in FIG. 2 the sections are arranged in order of increasing flexibility or decreasing' resistance to bending. The discs 22, 23, 24 are prevented ,from moving or sliding longitudinally to the right in FIG. 2 with respectl to the wires 20 by the loops at 26, 27, 28. To hprevent the discs from sliding in the opposite direction blocks jare provided in the form of pieces of tubing 30 of larger .jdiameter than the openings welded or otherwise fastened '5to the spring wires 20 at the face of each disc 22, 23, 24.

In FIG. 3, a preferred form ofvdifferential spring is shown i disposed within a water cooled cable 3l that is connected to a terminating block 32. The cable is provided with a longitudinally extending tube 33 of rubber or plastic and fabric which [defines a hollow core in the cablein which the differential v,spring is disposed. Surrounding the tube 33 are the `stranded fco'nductors34 that carry the current. Av heavy rubber jacket 35 is placed around the conductors to define the outer limits lof flow for the cooling water in the cable. The cooling water flows 'generally over, around and between the copperV conductors 34 within the area defined by the tube 33 on the inside and the jacket 35 on the outside. d

The copper conductors 34 are terminated between a cylinder 36 and a cup 37 that surrounds the cylinder. The ends fof the wires that form the least flexible section 17 of the dif- ,ferential spring are placed between the cup and cylinder along i with the conductors 34. The conductors and the end of the dif- .ferential spring are then soldered or brazed into position. The more lflexible sections 18 and 19 of the differential spring are ,disposed within the tube 33 and are attached thereto by clamps 39 and 40 that clamp the tube 33 to one or more of the V discs 22, 23,24. t

when the differential spring is used for supporting electrical Vcables 'that'carry heavy currents, such as a cable for supplying v .an electric arc furnace, the spring wires 20, forming the diffferential spring are preferably made of a nonmagnetic materi- :al such. as stainless steel to avoid induced heating from the rheavy currentscarried by the cable. The discs 22, 23, 24 are l:likewise preferably madeof a nonmagnetic material that is valso light and durable, for example, Micarta. f

differential spring 'willfurnish decreasing resistance to bending in they sections 17, 18,19, the maximum resistance occurring in section 17 nearest the termination point, thereby allowing the cable to *bend ina more natural arc. The differential spring, by connecting the tube 33 to the termination, also causes the tube to assist in supporting the'weight of the cable and cooling water which heretofore has been supported solely by the conductors Water cooled electrical cables are also made with a spiral spring as a hollow core defining means rather than the tube 33 shown in FIG. 3. The spiral spring is generally attached to the termination. In cables having a spiral spring the differential spring may be routed through the inside or around the outside 'of the spiral spring. The spiral spring may also be connected to the most flexible section of the differential spring. In that case the spiral spring is connected to the termination through the differential spring. `l The differential spring may also be mounted on the outside of the conductors 34. In that case the differential spring would,'of course, be of larger diameter and employ discs having a hollow core of appropriate diameter as shown in FIG. 4.

i' FIG. 4 illustrates my differential spring disposed about the exterior of a'watercooled electrical cable substantially the saine as that shown in FIG. 3. The ends of the spring wires 20 of the least flexible section 17 are strapped'to the cable adjacent the terminating block 32 by straps 42, 43 and 44. With this arrangement, the differential spring again provides differential resistance to cable bending, causes the cable to bend in a more natural gentle arc, and dampens cable sway and flexing. The arrangement shown in FIG. 4 is easily made and the differential spring can be applied to cables previously installed with a minimum of effort and inconvenience.

FIG.` 5 illustrates an alternate form of differential spring according to my invention. In this embodiment, each of the sections 17, 18, 19 comprises the same numberl of spring wires 49, 50, 51 respectively. The differential effect is obtained by using wires 49, 50, 51 of vdifferent thickness or diameter in the sections 17, `18 and 19, respectively, the largest diameter wire being used in section 17 to provide the least flexibility or greatest resistance to bending. The spring wires 49, 50, 51 instead of passing through the discs 22, 23, '24 are terminated on the faces of the respective discs by, for example, connection to a pin, staple, or other suitable meansanchored to the disc, as shown at 52. With this manner of terminating the spring wires 49, 50, 51, the sections of tubing 30 shown in the embodiment of FIG. 2 are unnecessary since the termination means itself will prevent sliding of the discs 22, 23, 24 with respect to the wires 49, 50, 5l.

The embodiment of FIG. 5 is slightly more complex and requires greater assembly time than the embodiment of FIG. 2, but because of the equal number of wires the sections are more balanced and symmetrical in useA than those in the embodiment of FIG. 2d.

It will be apparent to those skilled in the art that the problems associated with supporting any heavy flexible conduit, for example, a hose that carries cooling water for industrial applications, are quite similar to those encountered in supporting water cooled electrical cables. Accordingly, it will be understood that my invention is intended to encompass the` use of my differential spring for supporting vflexible conduits described.

While l have specifically illustrated4 and described a preferred and an alternate form and embodiment of my invention, changes, improvements, and additional uses will occur to those skilled in the art who come to understand its essential principles and accomplishments. l do not, therefore, wish to be confined to the specific forms and `uses of my invention herein specifically disclosed, nor in any other way inconsistent with the progress by which my invention has promoted the art.

lclaim:

l. In combination, an electrical cable having means defining a hollow core therein and having a terminal and means supporting said cable adjacent said terminal comprising a series of spring wire sections having different flexibilities joined end to end within said cable, said series being arranged to have a first end section of minimum flexibility and `to increase in flexibility in each section to a second end section of maximum flexibility, means attaching said first end section to said terminal, and means attaching said second end section to said hollow core defining means, whereby said hollow'core defining means is connected to said terminal through said sections to assist in supporting the weight of said cable.

2. The combination of claim l wherein said sections are formed of different numbers of parallel spring wires, the number of said spring wires decreasing in said sections from said first end section to said second end section.

3. The combination of claim 1 wherein said sections are formed of equal numbers of parallel spring wires, the thickness of said spring wires decreasing in said sections from said first end section to said second end section.

4. In combination, a flexible conduit having a hollow interior and a differential spring for supporting said conduit adjacent a termination to which it is connected comprising a series of spring wire sections having different flexibilities joined bility in each section to a second end section of maximum flexibility, said sections having a shape and size throughout their length conforming substantially to the shape and size of said interior, and means attaching said first end section to said termination.

5. The combination of claim 4 wherein said sections are formed of different numbers of parallel spring wires, the number of said spring wires decreasing in said sections from said first end section to said second end section.

6. The combination of claim 4 wherein said sections are formed of equal numbers of parallel spring wires, the thickness of said spring wires decreasing insaid sections from said firstlend section to said second end section.

7. Means for reinforcing a flexible conduit against bending and radial deformation comprising a series of spring wire secf tions having dierent flexbilities and means joining said sections end to end to have a common longitudinal axis, said series being arranged to have a first end section of minimum flexibility and to increase in flexibility in each section to a second end section of maximum flexibility, each section comprising a plurality of parallel spring wires defining a hollow cylinder and being flexible against radial deformation and against bending in any direction about said longitudinal axis.

8. The means as defined in claim 7 wherein said sections are formed of different numbers of parallel spring wires, the number of' said spring wires decreasing in said sections from said first end section to said second end section.

9. The means as defined in claim 7 wherein said sections are formed of equal numbers of' parallel spring wires, the thickness of said spring wires decreasing insaid sections from said first end section to said second end section. t 

